Expression and accumulation of normal and modified soybean glycinins in potato tubers

Safety assessment of genetically engineered potatoes with designed soybean glycinin: compositional analyses of the potato tubers and digestibility of the newly expressed protein in transgenic potatoes

“…The band corresponding to the puri®ed proglycinin was found in the tubers of Ag877, Ag891 and Ag921, as described previously. 5 Except for the band of glycinin, protein staining indicated almost similar electrophoretic pro®les between transgenic (Ag877, Ag891 and Ag921) and control (MQ and P127) potatoes, thus suggesting that the metabolism in transgenic potatoes was not disturbed by the introduction of intact or modi®ed glycinin genes (Fig 3(B)). …”

“…4 In order to improve the nutritional defects and to add novel physiological functions arising from glycinin, we have constructed transgenic potatoes with intact and modi®ed genes for soybean glycinin. 5 The modi®ed glycinins have been constructed to have a tetra-methionyl sequence in the hypervariable region or C-terminal variable region of the native glycinin (Fig 1). The insertion of the sequence complements sulfur amino acid de®ciency of the native glycinin and improves emulsifying and gel-forming activities of the protein.…”

Production of recombinant proteins in transgenic plants: Practical considerations

“…In several instances, recombinant proteins were not properly cleaved, which resulted in the accumulation of pro-proteins instead of mature proteins. Normal and modified prepro-glycinins were not correctly processed in tubers of transgenic potato (Utsumi et al, 1994), but were correctly processed in seeds, leaves, and stems of transgenic tobacco (Utsumi et al, 1993). The incorrect processing of the recombinant glycinins in potato tubers indicates that the vacuoles of potato tubers lack the enzymes necessary for proteolytic cleavage of proglycinins to mature glycinins (Utsumi et al, 1994).…”

“…One of the potential concerns for recombinant protein production is, will folding and assembly of synthesized proteins in transgenic plants be similar to that in the native host? Several studies involving recombinant proteins produced in plants have shown that the proteins can undergo self-assembly (Beachy et al, 1985;Hiatt et al, 1989;Hoffman et al, 1988;Shani et al, 1994;Utsumi et al, 1993Utsumi et al, , 1994. Wheat highmolecular-weight glutenin subunits were able to assemble into multimeric form in transgenic tobacco (Shani et al, 1994).…”

Recent Progress in Research and Technology on Soybeans

“…We can also improve the properties of the storage proteins by introducing various kinds of physiologically active peptides into the molecules on the basis of the threedimensional structures. In addition, transgenic rice (Momma et al, 1999) and potato (Utsumi et al, 1994) with glycinins have already been bred. On soybean oil, the genetic modification of the fatty acid composition has been carried out for the increase of the oil stability.…”